Apparatus for safeguarding the spacing between successive bodies, especially vehicles on a track

ABSTRACT

The present safeguarding apparatus assures that successive bodies, such as vehicles on a track, will not bump into each other even where the vehicles must pass through a track junction to travel in different directions. The bodies are equipped with transmitter and receiver means and the tracks are equipped with first and second attenuated electrical conductor means for transmitting signals from a preceding body to a succeeding body to measure the spacing between these bodies. Said first and second attenuated electrical conductor means are interconnected with each other by further conductor means at least in the area of said junction in such a manner that feeding a signal into the first or second electrical conductor at any given point in said junction area corresponds substantially to feeding said signal into the respective other of said first or second electrical conductor means at the respective opposite point.

United States Patent 11 1 Kraus June 24, 1975 [75] Inventor:

[73] Assignee: Messerschmitt-Boelkow-Blohm GmbH, Munich, Germany [22]Filed: Nov. 2, 1973 [21] Appl. No.: 412,254

Peter Kraus, Munich, Germany [30] Foreign Application Priority DataPrimary Examiner-M. Henson Wood, Jr. Assistant Examiner-Reinhard J.Eisenzopf Attorney, Agent, or Firm-W. G. Fasse; W. W. Roberts 57 IABSTRACT The present safeguarding apparatus assures that successivebodies, such as vehicles on a track, will not bump into each other evenwhere the vehicles must pass through a track junction to travel indifferent directions. The bodies are equipped with transmitter andreceiver means and the tracks are equipped with first and secondattenuated electrical conductor means for transmitting signals from apreceding body to a succeeding body to measure the spacing between thesebodies. Said first and second attenuated electrical conductor means areinterconnected with each other by further conductor means at least inthe area of said junction in such a manner that feeding a signal intothe first or second electrical conductor at any given point in saidjunction area corresponds substantially to feeding said signal into therespective other of said first or second electrical conductor means atthe respective opposite point.

10 Claims, 5 Drawing Figures APPARATUS FOR SAFEGUARDING THE SPACINGBETWEEN SUCCESSIVE BODIES, ESPECIALLY VEHICLES ON A TRACK BACKGROUND OFTHE INVENTION The present invention relates to an apparatus forsafeguarding the spacing between successive bodies, specially vehicleson a track, for example, in a local transit system or in metropolitanrailroad. In the past, ever increasing demands have been made for ahigher conveying performance as well as for an efficient cruising orschedule speed. However, these two conditions can be satisfiedsimultaneously only if a very high traffic density is permitted in theindividual track section. As a result, the safeguarding of the spacingbetween successive vehicles becomes especially important.

A high traffic density calls for sequencing durations between adjacentcars which last only a few seconds in transit systems employing socalled individual vehicles. However, sequencing durations of a fewseconds cannot be handled with the necessary spacing safety byconventional means such as a spot light signal or a so called linearinfluencing system. These conventional means are unsatisfactory becauseeach moving body or rather vehicle must control its speed and itsspacing from the preceding vehicles in response to the speed of thepreceding vehicle where the above mentioned short sequencing durationsare to be maintained. A basic requirement for this type of operationcalls for continuously informing each vehicles with regard to itsspacing from the respective preceding vehicle. Stated differently,supplying such information only at predetermined reference points willnot be sufficient. For this purpose US. patent application 277,783 filedAug. 3, 1972,Peter Kraus et al. now US. Pat. No. 3,836,770, discloses atransit system in which each vehicle is equipped with a transmittermeans and with a receiver means. Each receiver has a predetermined inputsensitivity. Further, in said previous system, the tracks are equippedwith electrical signal-conveying means providing a special predeterminedattenuation in such a manner that a signal emanating from thetransmitter means with a defined amplitude will be received by thereceiver means of the next following vehicle as an indication of thespacing between the two vehicles because the signal amplitude willdecrease in a defined manner as a function of the spacing from thetransmitter due to said attentuation. Preferably, the signal conveyingmedium is a homogenous, electrical conductor means which is attenuatedto such an extent that the amplitude of a signal coupled into theconductor means by a signal transmitter diminishes in a measurablemanner already after passing through a short length of said conductormeans, for example, after one meter. Therefore, it is possible to usethe amplitude of a signal at the location of a receiver means as ameasure for the spacing between the transmitter and receiver means. thatis between the two vehicles.

ln thesystem according to the above German patent publication, eachvehicle receives continuously through its receiver having a definedinput sensitivity, information regarding its spacing from the respectivepreceding vehicle as long as the transmitter of the preceding vehiclefeeds a signal of a defined amplitude into the attenuated electricalconductor means.

ln a system such as described in the above German patent publication,problems arise where the track comprises a junction with track branchesextending in different directions since it is necessary to avoidcollisions between a following vehicles and a preceding vehicle undertwo different aspects. First, collisions must be avoided betweenadjacent vehicles, both of which are intended to travel in the samebranch direction. Second, collisions must also be avoided between afollowing and a preceding vehicle where the preceding vehicle isintended to travel in another branch direction but is still within orahead of a junction departure area. Thus, the measurements of thespacing between adjacent bodies or vehicles, possibly in combinationwith information regarding the speed of the vehicles or bodies, must beemployed to control the spacing between adjacent vehicles to avoid bothof the mentioned collisions.

Another problem is posed in connection with the system described in theabove German patent publication by the need for avoiding that a thirdvehicle, which is still within the junction, but which has passed thejunction departure area, influences, for example by slowing down, themeasuring of the spacing or the safeguarding of the spacing between twovehicles which are intended to travel in the same direction.

The following text will refer to vehicles" generally. However, it is tobe understood that the present diclosure applies equally to any type ofbody moving along a track.

OBJECTS OF THE INVENTION In view of the above, it is the aim of theinvention to achieve the following objects singly or in combination:

to solve the above outlined problems, more specifically to assure thesafeguarding or proper spacings between ajacent vehicles moving along atrack, even when the track comprises a junction;

to provide a system in which a succeeding vehicle on a track receivesinformation regarding its spacing from two vehicles ahead of it on atrack including a junction, whereby the spacing infonnation shall besupplied continuously with regard to a preceding vehicle travelling inthe same direction as the following vehicle whereas the spacinginformation with regard to a preceding vehicle travelling in a differentdirection shall be supplied only as long as said preceding vehicletravelling in the different direction has not yet passed completelythrough a junction departure area;

to permit the stopping of a vehicle after it has passed a junctiondeparture area without causing by such stopping the deceleration of avehicle passing through the junction in another direction;

to avoid a collision of vehicles in the junction independently of thedirection of travel which has been selected for any particular vehicle;and

to provide a system in which the transmitter output power and thereceiver input sensitivity is variable in response to the speed of therespective vehicle.

SUMMARY OF THE INVENTION According to the invention there is provided anapparatus for safeguarding the spacing between successive bodies,especially vehicles on a track including a track junction with trackbranches extending into different directions wherein each vehicle isprovided with transmitter and receiver means for measuring the spaceingbetween adjacent vehicles. Along both sides of said track junction thereis arranged a respective homogenous, electrical conductor providing aspecial attenuation, wherein coupling means are provided for couplingthe transmitter and receiver means of the individual vehicles with theconductor extending in the direction in which the respective vehicle isintended to travel, and wherein further conductor means interconnect theattenuated, homogenous conductor means extending along the trackbranches, said further conductor means extending at least from thebeginning of the junction to the end of a junction departure area.Preferably, the further conductor means are arranged at uniformintervals relative to each other. The further conductor means maycomprise galvanic connections arranged at such narrow intervals relativeto each other that the coupling of a signal into one of the firstmentioned conductors at any point therealong corresponds substantiallyto the coupling of the signal into the other of the first mentionedconductors at the respective opposite point. Preferably, the narrowintervals between adjacent further conductor means are used up to theend of the junction departure area.

In the arrangement according to the invention one attenuating conductormeans will thus be provided for each track or branch, that is for eachdirection. Further, upon reaching the junction the transmitter andreceiver means of a vehicle will be coupled only to that attenuatingconductor which extends in the direction in which the vehicle isintended to travel in order to receive signals from a preceding vehicleintended to travel in the same direction for the measuring orcontrolling of the spacing of the following vehicle from the precedingvehicle. However, due to the interconnection which is provided accordingto the invention between the two attenuating electrical conductor means,the following vehicle is also capable to receive signals from apreceding vehicle which is intended to travel in a different direction,even though the receiver of the vehicle has been coupled to but one ofsaid attenuating conductor means. Accordingly, collisions with such avehicle intended to travel in another direction will also be avoided aslong as there is a danger of such a collision, that is, as long as thepreceding vehicle travelling in the other direction has not yet clearedthe junction departure area. After a vehicle travelling in anotherdirection has passed the junction departure area, it is not capable ofinfluencing the travel of the following vehicle which is intended totravel in the opposite direction. This feature of the invention has theadvantage that a traffic jam in a track branch downstream of a junctiondeparture area will not affect the flow of traffic, the vehicles ofwhich are intended to travel along the opposite branch of the junction.

BRIEF FIGURE DESCRIPTION In order that the invention may be clearlyunderstood, it will now be described, by way of example, with referenceto the accompanying drawings, wherein:

FIG. 1 illustrates a schematic plan view of a track section with ajunction and two track branches wherein an electrical conductor extendsalong each rail of the track and into the respective track branch;

FIG. 2 illustrates a sectional view through one of the electricalconductor means extending along the rails of FIG. 1, whereby theconductor means is arranged in the gap between two U-shaped iron coresof a coupling means, such as a coupling coil;

FIG. 3 illustrates a perspective view of a section of one of theattenuating electrical conductor means used in FIG. 1;

FIG. 4 is a simplified plan view of a track and junction illustratingthe interconnection between the electrical conductor means extendingalong the rails as illustrated in FIG. 1; and

FIG. 5 is a schematic plan view similar to that of FIG. 1 butillustrating amplifier means interconnecting the attenuating electricalconductor means as well as simulating circuit means interconnectingcertain of the amplifiers with each other.

DETAILED DESCRIPTION OF EXAMPLE EMBODIMENTS FIG. 1 illustrates threevehicles 1, 2, and 3 which constitute so called individual transportfacilities of a local transit system. These vehicles travelautomatically and without stopping between a point of departure and apoint of arrival. These vehicles 1, 2 and 3 cannot pass each other aslong as the vehicles are on the same course or track. For this purpose,it is possible to use one tracer guide for the vehicles, for example inthe form of a track, rail or the like. The vehicles 1, 2 and 3 arelocated on the track section 4, 5 and 6 interconnected by a junction.The directions of vehicle advance are indicated by the arrows 7, 8 and9. Thus, the vehicles travel through the junction in the direction of adecentralization whereby the last vehicle 3 is intended to make a leftturn when passing through a junction departure area 10 which is markedby a broken line circle in FIGS. 1, 4 and 5 of the drawings. By makingthe left turn, the vehicle 3 will pass from the track section 4 into thetrack section or branch track 5. For the illustrated vehicle sequencesuch a left turn by the vehicle 3 is possible only when the vehicle 2,which is intended to make a right turn into the branch track 6, haspassed through the junction departure area 10. Stated differently, thevehicle 2 must have completely cleared the railway loading gauge of thetrack sections 4 and 5. As illustrated in FIG. 1, vehicle 2 has not yetcompletely cleared the track sections 4 and 5. Accordingly, in order toavoid a collision between the vehicle 3 and the vehicle 1, as well asbetween the vehicle 3 and the vehicle 2, the vehicle 3 must receiveinformation regarding its spacing relative to both vehicles ahead of iton the left track branch 5 and on the right track branch 6. The travel,or rather the speed of the vehicle 3 must be determined accordingly aslong as the vehicle 2 has not yet completely cleared the junctiondeparture area 10. As soon as the vehicle 2, making a right turn, hascleared the junction departure area 10, the last vehicle 3 shall receiveinformation only regarding its spacing relative to the vehicle 1, whichhas made a left turn corresponding to the turn intended to be made bythe vehicle 3. In other words, the speed or travel of the vehicle 3shall depend only on the speed or travel of the vehicle 1 after thevehicle 2 has cleared the area 10. The manner in which all of theseconditions may be met shall now be elucidated in more detail.

As illustrated .in FIG. 1 all vehicles 1, 2 and 3 are equipped withtransmitter means 11 and receiver means 12. These transmitter andreceiver means are inductively coupled with the attenuating first andsecond electrical conductor means 13 and 14. The electrical conductormeans 13 extend along the tracks 4 and 5 whereas the electricalconductor means 14 extend along the tracks 4 and 6. These electricalconductor means 13 and 14 are of the same construction and provide apredetermined attenuation along their length as will be described inmore detail below. The transmitter means 11 may, for example, compriseknown generators for producing a high frequency alternating current. Forexample, transistor generators may be suitable for this purpose. Thetransmitter 11 may be connected by means of a selector switch (notshown) either to a couplingcoil 11 arranged on the left longitudinalside of the vehicle or to the coupling coil 11'' arranged on the rightlongitudinal side of the respective vehicle 1, 2 and 3.

The receiver means 12 may each comprise a conventional transistoramplifier which is also connectable by means of a selector switch (notshown) either with a coupling coil 12 arranged on the left longitudinalside of the respective vehicle or with a coil 12" arranged on the rightlongitudinal side of the respective vehicle.

All of the coupling coils 11', 11" and 12', 12" which are provided forthe transmitter means 11 and for the receiver means 12, are of the sameconstruction with the possible exception of the number of turns. Theconstruction of these coils is schematically shown in FIG. 2 wherebyonly one of the coils l l is illustrated in connection with one of theelectrical conductor means 13 as mentioned above. The winding 15 of thecoil is symmetrically distributed over two U-shaped iron cores 17 havingthe same dimensions and defining an air gap 16. The iron cores 17 arearranged symmetrically relative to the conductor 13 which extendslongitudinally through the air gap 16. In the illustrated arrangement orstructure of the coils ll, 11", 12' and 12" the magnetic'stray flux orleakage will be small relative to the effective flux in the air gaps 16or in the iron cores 17. In addition, the magnetic flux will behomogenized in the air gaps. This has the advantage that the efficiencyof the transmitter means 11 is at a maximum whereas the sensitivity ofthe receiver means 12 relative to magnetic stray fields will be at aminimum.

FIG. 2 further illustrates that the electrical conductor 13 and thus theelectrical conductor 14 comprises three parallel conductor members 18.The spacings between the center conductor member and the two outerconductor members are the same. Such a symmetric conductor 13 has asubstantially heigher stability against disturbing effects thanconventional twin conductors.

Since it is not possible to completely avoid that the vehicles I, 2 and3 and thus the respective coils ll, 11'', 12', 12" make lateralmovements relative to the conductors l3, l4=while traveling along thetrack, the width of the pole pieces 19 of the iron cores 17 is smallerthan the spacing between the center conductor member 18 and the outerconductor members 18 or the electrical conductor means. However, thewidth of the conductors l3, 14 is larger than the width of the ironcores 17. This construction has the advantage that both conductor loops20 are uniformly exposed to the magnetic flux even if the coils 11',11", 12' and 12" should be laterally displaced relative to the conductormeans I3, 14. The sliding of the conductor means 13 and 14, along thepole pieces 19, for example due to lateral back and forth movement ofthe vehicles 1, 2, and 3, may be prevented by making the air gaps 16sufficiently influence on the coupling between the coils and therespective conductor 13 or 14 if the coils ll, 11', 12', and 12" areconstructed as described above, namely, when the coils comprise twowindings 15 which are symmetrically distributed on two iron cores 17.

As mentioned, both conductor means 13 and 14 as shown in FIG. 1 are ofthe identical construction. As may be seen from FIG. 3 the individualconductor members 18 are so called flat strip copper conductors or thelike which are embedded together with a conducting foil 21 in a sheeth22 of synthetic material. The conducting foil 21 may, for example,comprise a carbon coated fleece of synthetic material. The individualconductor members 18 are connected with each other in a conductingmanner along their entire length by the conducting foil 21. However, theconductivity of this cross connection is substantially smaller than thatof the conductor members 18. The combination of the substantial ohmiccross leakage with the longitudinal or series impedance of the conductormembers 18 provides the strong attenuation along the conductor means 13and 14 mentioned above. The amplitude of a signal travelling along suchespecially attenuated homogeneous conductor means diminishes in ameasurable manner already after having passed through a short length ofthe conductor means, for example after one meter. The signal amplitudeof the signals which have been coupled into the conductor means throughthe coils l l large. S'uch'back and forth movements are without any or11" diminishes in accordance with an exponential function having anegative exponent. Accordingly, the amplitude of the signal at anyrandom point along the conductor means is a measure for the spacingbetween this random point and the respective transmitter means 11 orrather the respective coupling coil 1 l or 1 1''. As a result, the lastvehicle 3, for example, is able to receive through its receiving means12 having a defined input sensitivity, information regarding its spacingrelative to the vehicle 1 moving along the left track branch 5. Suchinformation is supplied as long as the transmitter means 11 of thevehicle 1 couple a high frequency alternating current signal into theconductor means 13 through the coil 11' and as long as the conductormeans 13 are coupled to the coil 12 of the receiving means 12 of thelast vehicle 3.

Where, due to a high traffic density, the spacing between adjacentvehicles is extremely small, the information regarding such spacingalone is not sufficient to prevent a collision between adjacentvehicles. Therefore, according to the invention the transmitting powerof the transmitter means 11 and the input sensitivity of the receivermeans 12 is variable as a function of the speed of the respectivevehicle. The transmitting power of each transmitter means 11 reaches itsmaximum when the respective vehicle 1, 2 or 3 is stopped. When thevehicle travels at its maximum speed the transmitting power is at itsminimum. Contrary thereto, the input sensitivity of each receiving means12 is at its minimum when the vehicle is stopped and at its maximum whenthe vehicle travels at its maximum speed. To this end, the transmittermeans 11 and the receiver means 12 of each vehicle may be controlled bya voltage which may be derived for example from a generator voltageproduced by a generator driven by a wheel of the vehicle.

It will be appreciated that due to the above feature, the last vehicle 3will receive an information for the control of its travel and brakingaction as long as the transmitter means 11 of the vehicle 1 travellingon the left branch track transmits a signal. The received signal willdepend from the speed of the receiving vehicle and from the speed of thepreceding transmitting vehicle and from the spacing between the twovehicles. Ac cordingly, the received information is suitable forcontrolling the travel characteristics of the receiving vehicle 3 insuch a manner that a collision with the transmitting vehicle 1 isimpossible. To this end, the vehicle drive means (not shown) areprovided with a control member to which the information signals receivedby the vehicle 3 are supplied as a reference input valve. The controlmember also receives the above mentioned generator derived controlvoltage. The reference value and the control voltage are combined witheach other in such a manner that an automatic braking action is appliedto the vehicle when the control voltage exceeds the reference voltage.Accordingly, the fact that the control value exceeds the reference valueis always an indication that the receiving vehicle 3 has a higher speedthan the preceding transmitting vehicle 1 and/or that the spacingbetween the two vehicles is too small for the speed difference.

In the light of the foregoing description it will be appreciated thatthe travel characteristics of the last vehicle 3 are determined by thetravel characteristics of the vehicle 1 travelling ahead of the vehicle3 along the left track branch 5 whereby the mentioned transmitter means11 and the receiver means 12 with their respective coils l l and 12' areemployed in combination with the attenuated electrical conductor means13. In order to assure that the last vehicle 3 will also not collidewith the vehicle 2 which is still in the junction departure area butwhich is intended to make a right turn along the track branch 6, theelectrical conductor means 13 extending in the direction of travel ofthe vehicles l and 3, and the electrical conductor means 14 extending inthe direction of travel of the vehicle 2, are interconnected with eachother by galvanic connections 23. Preferably, these galvanic connections23 which constitute further conductor means are arranged at uniformintervals relative to each other and extend from the beginning B of thejunction to the end E of the departure area 10 as schematicallyillustrated in FIG. 4. The intervals between adjacent connections 23may, for example, have a width of a few centimeters. Due to theseinterconnections 23, the coupling of a signal into one of the conductormeans 13 or 14 at any random point A corresponds substantially to thedirect coupling of the signal into the respective opposite conductor 14or 13 at the corresponding opposite point A. As a resuit, as long as thevehicle 3 travels between the beginning B of the junction and the end Eof the junction departure area 10 its receiver coils 12 will alsoreceive a signal from the vehicle 2 making a right turn, which signal iscoupled to the conductor means 14 by the respective coil 11 of thetransmitter means 11 of the vehicle 2. This is so even though the coil12' is coupled with the conductor means 13. This signal at the positionof the coil 12 of the receiving means 12 of the last vehicle 3corresponds in its amplitude and phase substantially to the signal whichwould be received if the receiver means 12 were coupled with its coil12" with the conductor means 14. Therefore, the vehicle 3 will becontrolled or react in such a manner as if the vehicle 2, making a rightturn, where in front of the vehicle 3 and travelling in the samedirection as is intended for the vehicle 3. If the spacing between thevehicles 2 and 3 is too small, that is if the vehicle 3 cannot passthrough the junction departure area 10 without interferrence by thevehicle 2, the vehicle 3 will be automatically subjected to a brakingaction due to the signal received from the vehicle 2. However, this ispossible only as long as the vehicle 2 intending to make a right turnhas not yet completely cleared the junction departure area 10. Aftersuch clearing is completed, the vehicle 2 can transmit signals only tovehicles following in the same branching direction since theinterconnections 23 between the conductor means 13 and 14 do not extendbeyond the end E of the junction departure area 10. In other words, oncethe vehicle 2 has cleared the area 10 only vehicles which are coupledwith their receiver coils 12" to the conductor means 14 can receivesignals from the vehicle continuing its travel on the track branch 6.This feature of the invention has the advantage that, for example,vehicles which have passed the junction departure area 10 after havingmade a right turn, can stop without causing a braking action in vehicleswhich negotiate the junction departure area in a left turn.

In view of the foregoing description of the apparatus according to theinvention it will be appreciated that a collision between a followingvehicle and a preceding vehicles is definitely prevented regardless ofwhich direction any individual vehicle is intended to take. Uponreaching the junction it is merely necessary that the transmitter means11 and the receiver means 12 of the vehicles are coupled to theconductor means 13 or 14 which extend in the direction of travel inwhich the respective vehicle is intended to proceed. A respectiveactuation of the selector switch, which is arranged between thetransmitter means 11 and the receiver means 12 and the respective coilsll, 11" or 12, 12", may, for example, be accomplished in connection withthe steering mechanism of the vehicles. Accordingly, the selector switchwill be actuated in response to the operation of the steering mechanismfor a left or right turn. Suitably, all of the transmitter and receivermeans of the vehicles are coupled only with one common conductor means13 or 14 prior to entering into the junction.

Since the propagation of a signal emanating from a transmitter means 11is symmetrical in both directions of a conductor means 13 or 14, thatis, the signal also propagates in the direction of vehicle advance asindicated by the arrows 7, 8 and 9, it is possible that a transmittedsignal may influence the receiving means 12 of the vehicle from whichthe signal has been transmitted. in order to avoid such a selfinfluence, so to speak, for example of the receiving means 12 of thelast vehicle 3 by a signal emanating from the transmitter means 11 ofsaid vehicle 3, there is provided according to the invention acompensating transmitter means 24 which is arranged between thetransmitter means 11 and the receiver means 12 of each vehicle 1, 2 and3. This com pensating transmitter means 24 is coupled to the re spectiveconductor means 13 or 14. The compensating transmitter means 24correspond in their structure substantially to the transmitter means 11described above whereby these compensating transmitter means 24 may alsobe coupled selectively through a selector switch (not shown) either witha coil 24' arranged along the left longitudinal side or with a coil 24"arranged on the right longitudinal side of the respective vehicle 1, 2and 3. These coils 24 and 24" also correspond in their structure and intheir arrangement relative to the conductors 13 or 14 to the coils 11"or 11" of the transmitter means 11 provided for the measuring purposes.

Each compensating transmitter means 24 transmits a signal having anamplitude corresponding to the amplitude of the signal transmitted bythe measuring transmitter means 11 of the same vehicle at the locationof the compensating transmitter means whereby a phase shift of 180 isprovided between the two signals at said location. As a result, thesignal of the measuring transmitter means 11 is substantially erased atthe location of the compensating transmitter means 24 withoutsubstantially influencingthe propagation of this signal in therespective conductor ineans 13 or 14 in the direction toward the nextfollowing vehicle. Due to the further conductor means 23 between theconductor means 13 and l4, each compensating transmitter means 24produces simultaneously a signal in both conductors l3 and 14.Therefore, it is assured that in the area of the conductors 23 a signalfrom the measuring transmitter means 11 will not substantially propagatebeyond the location of a respective compensating transmitter means 24.

Incidentally, the vehicles 1, 2 and 3 have been omitted in FIGS. 4 and 5for simplicitys sake and in order to facilitate the illustration of thefurther conductor means 23.

In the embodiment of FIG. 4, the further conducto means 23 extenddirectly between the first and second conductor means 13 and 14galvanically interconnecting these first and second conductor means. Inthe modification according to FIG. 5, the further conductor meanscomprise amplifiers or 26 which, for example, may be conventionaltransistor amplifiers. These amplifiers are used in the furtherconductors beginning at the junction and extending to the end of thejunction departure area 10. The amplifiers 25 permit the transmittal ofsignals from the left conductor means 13 into the right conductor means14 as viewed in the direction of vehicle advance. The amplifiers 26 onthe other hand, permit the signal transmission in the oppositedirection. This is illustrated in FIG. 5 for a short section of thetrack portion 4. As compared to the arrangement of FIG. 4, fewer furtherconnections are required in the embodiment of FIG. 5. Where amplifiersare used in the further conductor means, the intervals between suchfurther conductor means with amplifiers feeding into the same first orsecond conductor means 13 or 14 may have a width which is smaller thanthe smallest possible spacing from center to center between two vehiclesimmediately following each other. As long as said intervals have thejust defined width, it is assured that even where there is a smallerspacing between two vehicles, each of which is intended to turn in adifferent advance direction, the preceding vehicle will be able totransmit signals to the following vehicle. Suitably the amplifiers 25and 26 are operated with a strong negative feed-back and provide anamplification or gain of l In this manner it is assured that the signalsappearing at the outputs of the amplifiers 26, which are connected tothe conductor means 13, are the same with regard to amplitude and phaseposition as the signals at the inputs of these amplifiers connected tothe conductor means 14. Accordingly, in the arrangement of FIG. 5, thecoupling of a signal into one of the conductors 13 or 14 at the locationof an amplifier 25 or 26 corresponds to directly coupling this signalinto the respective other conductor means 14 or 13 at the respectiveopposite location.

According to the invention, it is assured that a signal transmittedthrough an amplifier 25 or 26 can propagate in the respective conductor14 or 13 in the direction of vehicle advance only in the limited manner,namely only up to the feed-in point of the next amplifier 25 or 26connected to the same conductor 14 or 13. This is accomplished bysimulation circuit means 27 or 28 which are connected in phaseopposition between the input and output of the two adjacent amplifiersfeeding into the same conductor 13 or 14 whereby the simulating circuitmeans constitute a simulation of the respective conductor means 13 or 14extending between the two amplifiers. Thus, in the embodiment of FIG. 5,the amplifier 26 which is located closer to the junction departure area10 will, for example, compensates the signal which is present at itsfeedin point in the conductor means 13 if the other amplifier 26 whichis located more remote from the junction departure area 10, feeds asignal into the conductor means 13.

Incidently, it should be mentioned here that in the embodiments of FIGS.4 and 5, transformer could be connected into the further conductor meansinterconnecting the conductor means 13 and 14 in order to keepinterferring potentials out of the entire system.

Although the invention has been described with reference to specificexample embodiments, it is to be understood, that it is intended tocover all modifications and equivalents within the scope of the appendedclaims.

What is claimed is:

1. An apparatus for safeguarding the spacing between successive bodies,especially vehicles on a track including a track junction with trackbranches extending into different directions, comprising transmitter andreceiver means on each body for measuring the spacing between adjacentbodies, first and second homogenous electrical conductor means having apredetermined signal attenuation, and extending along said track andincluding respective conductor portions extending along said trackbranches, coupling means operatively arranged for coupling saidtransmitter and receiver means to that electrical conductor means andportion thereof extending along the track branch on which the body isintended to travel, and further electrical conductor meansinterconnecting said first and second conductor means at predeterminedintervals therealong, said further electrical conductor means startingat least at the beginning of said junction in the track and continuingto the end of an area where a body leaves the junction, said signalattenuation deter mining the distance of signal transmission.

2. The apparatus according to claim 1, wherein the intervals betweenadjacent ones of said further conductor means are of uniform width.

3. The apparatus according to claim 1, wherein said transmitter meanscomprise signal generating means for transmitting signals having apredetermined amplitude, and wherein said receiving means having apredetermined sensitivity.

4. The apparatus according to claim 1, further comprising compensatingtransmitter means arranged between said transmitter means and saidreceiver means on the respective body and further coupling meansarranged for coupling said compensating transmitter means to therespective one of said first or second electrical conductor means.

5. The apparatus according to claim 1, wherein the intervals betweenadjacent ones of said further conductor means interconnecting said firstand second conductor means have such a narrow width that coupling of asignal into one of said first or second conductors at any pointherealong corresponds substantially to directly coupling said signalinto the corresponding opposite point along the respective other firstor second conductor.

6. The apparatus according to claim 1, comprising amplifier means aspart of said further electrical conductor means, wherein those furtherconductor means the amplifier means of which feed into the same of saidfirst or second electrical conductor means, are spaced from each otherat a distance which is smaller than the smallest possible spacing fromcenter to center between immediately adjacent bodies.

7. The apparatus according to claim 6, further comprising simulationcircuit means for coupling each amplifier means in phase opposition toat least one other amplifier means feeding into the same first or secondelectrical conductor means, said simulation circuit means constituting asimulation of the portion of the first or second electrical conductormeans extending between the outputs of the coupled amplifier means.

8. The apparatus according to claim 7, wherein said simulation couplingcircuit means are arranged to couple each amplifier means to the nextadjacent amplifier means feeding into the same first or secondelectrical conductor means.

9. The apparatus according to claim 7, wherein said simulation couplingcircuit means are arranged to couple each amplifier means to at leastone other amplifier means arranged in front thereof in the direction oftravel of the bodies and feeding into the same first or secondelectrical conductor means.

10. The apparatus according to claim 1, wherein the intervals betweenadjacent ones of said further electrical conductor means have a width ofa few centimeters.

1. An apparatus for safeguarding the spacing between successive bodies,especially vehicles on a track including a track junction with trackbranches extending into different directions, comprising transmitter andreceiver means on each body for measuring the spacing between adjacentbodies, first and second homogenous electrical conductor means having apredetermined signal attenuation, and extending along said track andincluding respective conductor portions extending along said trackbranches, coupling means operatively arranged for coupling saidtransmitter and receiver means to that electrical conductor means andportion thereof extending along the track branch on which the body isintended to travel, and further electrical conductor meansinterconnecting said first and second conductor means at predeterminedintervals therealong, said further electrical conductor means startingat least at the beginning of said junction in the track and continuingto the end of an area where a body leaves the junction, said signalattenuation determining the distance of signal transmission.
 2. Theapparatus according to claim 1, wherein the intervals between adjacentones of said further conductor means aRe of uniform width.
 3. Theapparatus according to claim 1, wherein said transmitter means comprisesignal generating means for transmitting signals having a predeterminedamplitude, and wherein said receiving means having a predeterminedsensitivity.
 4. The apparatus according to claim 1, further comprisingcompensating transmitter means arranged between said transmitter meansand said receiver means on the respective body and further couplingmeans arranged for coupling said compensating transmitter means to therespective one of said first or second electrical conductor means. 5.The apparatus according to claim 1, wherein the intervals betweenadjacent ones of said further conductor means interconnecting said firstand second conductor means have such a narrow width that coupling of asignal into one of said first or second conductors at any pointherealong corresponds substantially to directly coupling said signalinto the corresponding opposite point along the respective other firstor second conductor.
 6. The apparatus according to claim 1, comprisingamplifier means as part of said further electrical conductor means,wherein those further conductor means the amplifier means of which feedinto the same of said first or second electrical conductor means, arespaced from each other at a distance which is smaller than the smallestpossible spacing from center to center between immediately adjacentbodies.
 7. The apparatus according to claim 6, further comprisingsimulation circuit means for coupling each amplifier means in phaseopposition to at least one other amplifier means feeding into the samefirst or second electrical conductor means, said simulation circuitmeans constituting a simulation of the portion of the first or secondelectrical conductor means extending between the outputs of the coupledamplifier means.
 8. The apparatus according to claim 7, wherein saidsimulation coupling circuit means are arranged to couple each amplifiermeans to the next adjacent amplifier means feeding into the same firstor second electrical conductor means.
 9. The apparatus according toclaim 7, wherein said simulation coupling circuit means are arranged tocouple each amplifier means to at least one other amplifier meansarranged in front thereof in the direction of travel of the bodies andfeeding into the same first or second electrical conductor means. 10.The apparatus according to claim 1, wherein the intervals betweenadjacent ones of said further electrical conductor means have a width ofa few centimeters.